Morphology of two marine woloszynskioid dinoflagellates Biecheleria brevisulcata sp. nov. and Biecheleriopsis adriatica (Suessiaceae, Dinophyceae) from Japanese coasts (vol 53, pg 52, 2014)

The morphology of two marine woloszynskioid dinoflagellates from the Japanese coast was examined by light, scanning and transmission electron microscopy, and phylogenetic positions were inferred on the basis of partial nuclear-encoded large-subunit ribosomal (r) DNA (D1-D3) sequences. Both species had a single elongate apical vesicle (EAV) on the anterior end, a diagnostic feature of the Suessiaceae, and were identified as Biecheleriopsis adriatica and an undescribed species of Biecheleria. Cells of the undescribed Biecheleria were spherical to ellipsoidal with parietal chloroplasts, conspicuous pyrenoids, an eyespot, and a nucleus located anteriorly. Transmission electron microscope observations revealed penetrations of the thylakoid into the pyrenoid matrix and an eyespot composed of a stack of cisternae containing several brick-like materials (type E). This species had a total of nine to 10 latitudinal series of amphiesmal vesicles (AVs), including three to four epiconal, three cingular, and three hypoconal series. Nineteen small globular knobs were present on the EAV. This species was distinguished from other marine woloszynskioids by cell size, position of nucleus, and the number of AV series and EAV knobs, i.e. previously reported Biecheleria have more than 25 knobs. We describe a new marine woloszynskioid dinoflagellate Biecheleria brevisulcata sp. nov. The Japanese strains of Bps. adriatica had 11-12 series of AVs in total, including four to five epiconal, three cingular, and four hypoconal series, and there were 32 knobs on the EAV. The features of these strains basically coincided with those of the original description of Bps. adriatica, but differed in the larger number of EAV knobs. Molecular phylogeny also indicated their affinity to the Suessiaceae. Strains of B. brevisulcata formed a clade related to B. baltica and B. cincta. The two genera, Biecheleria and Biecheleriopsis, have a strong morphological resemblance to one another, and they were distinguished only by rDNA sequences and the presence of a fibrous flagellar root (nuclear connective). This study also showed a morphological difference between the two genera; vesicles of the third row of cingular vesicles were larger and the lower cingular margin had a zigzag line in Biecheleria, whereas they were smaller and formed a straight line in Biecheleriopsis, especially on the dorsal side.